Primary Intrathoracic Dermatofibrosarcoma Protuberans

Pediatric dermatofibrosarcoma protuberans: A clinicopathologic and genetic analysis of 66 cases in the largest institution in Southwest China

Background

Dermatofibrosarcoma protuberans (DFSP) is an uncommon cutaneous tumor in children. Most published articles are sporadic or small series and lack systematically molecular analyses. The aim of our study is to better understand the clinicopathologic and genetic features of these rare lesions.

Methods

All patients diagnosed with DFSP aged ≤ 18 years were retrospectively reviewed from January 2006 to May 2022.

Results

A total of 66 cases (32 male and 34 female patients) were identified, with ages ranging from 0.3 to 18 years (median, 13 years). Tumor locations predominantly occurred on the trunk (38/66, 57.6%), followed by the extremities (20/66, 30.3%) and head/neck (8/66, 12.1%). Histological findings revealed classic (41/66, 62.1%), myxoid (4/66, 6.1%), pigmented (6/66, 9.1%), plaque-like (3/66, 4.5%), giant cell fibroblastoma (GCF; 6/66, 9.1%), and fibrosarcomatous (6/66, 9.1%) variants of DFSP. Immunochemistry revealed minority tumors (9/66, 13.6%) showing patchy or negative staining for CD34. Fluorescence in situ hybridization (FISH) indicated that 49 of 53 tested cases including all detected biopsy specimens (11/11) contained COL1A1-PDGFB fusion, in which the average copy number gain of COL1A1-PDGFB was 0.68. There were four cases negative for COL1A1-PDGFB rearrangement, one of which was found to harbor a novel COL3A1-PDGFB fusion by next-generation sequencing (NGS). Treatment for 63 patients comprised 40 marginal excisions and 23 wide local excisions (WLEs), including 1 with imatinib therapy. Follow-up information was available on 49 patients with a duration of 12-161 months (median, 60 months). Fourteen patients developed tumor recurrence, all with initial marginal excisions. The others survived with no evidence of disease.

Conclusions

This study of pediatric DFSP indicates certain discrepancies in clinicopathologic characteristics between children and adults. The majority of pediatric DFSPs contain COL1A1-PDGFB fusion, the same as their adult counterparts. The COL3A1-PDGFB chimerism might be associated with the special morphology of GCF, which needs further investigation. FISH is valuable in biopsy tissues and cases with atypical CD34 immunostaining, while supplementary NGS could be helpful to identify the cytogenetically cryptic DFSP. Overall, an urgent accurate diagnosis is needed to formulate an optimal therapeutic strategy in the pediatric population.

Dermatofibrosarcoma protuberans, fibrosarcomatous variant: A rare tumor in children

Fibrosarcomatous transformation of dermatofibrosarcoma protuberans is associated with a significantly worse prognosis in adults, but is a very rare feature in the pediatric population. Here, we report a case that occurred in a child. The diagnosis of fibrosarcomatous transformation of dermatofibrosarcoma protuberans was confirmed by a histopathological assessment and fluorescence in situ hybridization. A comparison with eleven other patients reported in the literature revealed that the local recurrence and mortality rates in children are similar to those observed in adults.

Fine-needle aspiration of dermatofibrosarcoma protuberans metastasizing to hemithorax with superior vena cava compression: Case report and literature review

Dermatofibrosarcoma protuberans (DFSP) is a low-grade spindle cell tumor of the skin commonly arising on the trunk and extremities which tends to be slow growing yet locally aggressive. DFSPs are associated with a good prognosis when surgical excision with negative margins is achieved. Although local recurrences occur up to 50% of incompletely resected cases, distant metastases are very rare. Here, we report a case of DFSP metastasizing to the right hemithorax diagnosed by an endobronchial ultrasound-guided fine-needle aspiration (FNA) 9 years after initial presentation. The aspirate showed a bland spindle cell proliferation that was morphologically similar to the original skin excision; the storiform pattern was particularly prominent in tumor-tissue fragments in the cellblock. Immunostaining showed strong, diffuse positivity for CD34. Molecular studies demonstrated a characteristic COL1A1/PDGFB fusion in both original and metastatic specimens. A review of the literature revealed that metastatic DFSP most often involves the lungs, occurs usually in cases with fibrosarcomatous transformation and after a local recurrence, and presents on average 4.5 years after the original diagnosis. This case did not show fibrosarcomatous transformation or local recurrence prior to metastasis 9 years later. In summary, it is important to consider the potential for metastases years after a nonrecurring primary DFSP, despite its rarity. Cytologic features when complemented by ancillary studies and awareness of the patient's prior clinical history permit a confident diagnosis of metastatic DFSP by FNA. In addition, by confirming the characteristic translocation, tyrosine-kinase inhibitor imatinib can provide additional treatment options for unresectable metastatic DFSP.

Undifferentiated Sarcomas in Children Harbor Clinically Relevant Oncogenic Fusions and Gene Copy-Number Alterations: A Report from the Children's Oncology Group

Purpose: A comprehensive analysis of the genomics of undifferentiated sarcomas (UDS) is lacking. We analyzed copy-number alterations and fusion status in patients with UDS prospectively treated on Children's Oncology Group protocol ARST0332.Experimental Design: Copy-number alterations were assessed by OncoScan FFPE Express on 32 UDS. Whole-exome and transcriptome libraries from eight tumors with sufficient archived material were sequenced on HiSeq (2 × 100 bp). Targeted RNA-sequencing using Archer chemistry was performed on two additional cases.Results: Five-year overall survival for patients with UDS was 83% (95% CI, 69%-97%) with risk-adapted therapy (surgery, chemotherapy, and radiotherapy). Both focal and arm-level copy-number alterations were common including gain of 1q (8/32, 25%) and loss of 1p (7/32, 22%), both of which occurred more often in clinically defined high-risk tumors. Tumors with both loss of 1p and gain of 1q carried an especially poor prognosis with a 5-year event-free survival of 20%. GISTIC analysis identified recurrent amplification of FGF1 on 5q31.3 (q = 0.03) and loss of CDKN2A and CDKN2B on 9p21.3 (q = 0.07). Known oncogenic fusions were identified in eight of 10 cases analyzed by next-generation sequencing.Conclusions: Pediatric UDS generally has a good outcome with risk-adapted therapy. A high-risk subset of patients whose tumors have copy-number loss of 1p and gain of 1q was identified with only 20% survival. Oncogenic fusions are common in UDS, and next-generation sequencing should be considered for children with UDS to refine the diagnosis and identify potentially targetable drivers. Clin Cancer Res; 24(16); 3888-97. ©2018 AACR.

Current treatment options for dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is rare, infiltrating dermal neoplasm, characterized by indolent growth and low probability of metastases. The critical event in DFSP development is the rearrangement of chromosome 17 and 22, leading to transcriptional up-regulation of platelet-derived growth factor, providing an autocrine and/or paracrine stimulus. The cornerstone of treatment for localized DFSP is complete surgical resection with microscopically negative margins. Adjuvant radiotherapy is suggested in cases of positive margins when re-excision is not feasible. The first effective systemic therapy in DFSP introduced into clinical practice was imatinib, demonstrating dramatic activity in advanced cases. Current results indicate that some DFSP patient initially evaluated as unresectable/metastatic or necessitating mutilating surgery turned resectable after imatinib therapy and this rational approach leading to complete remission maybe potentially curative. The clinical experience with other tyrosine kinase inhibitors is limited and imatinib remains the gold standard treatment of locally unresectable/metastatic DFSP. This review summarizes state of the art and perspectives on the DFSP management.

The role of cytogenetics and molecular diagnostics in the diagnosis of soft-tissue tumors

Soft-tissue sarcomas are rare, comprising <1% of all cancer diagnoses. Yet the diversity of histological subtypes is impressive with >100 benign and malignant soft-tissue tumor entities defined. Not infrequently, these neoplasms exhibit overlapping clinicopathologic features posing significant challenges in rendering a definitive diagnosis and optimal therapy. Advances in cytogenetic and molecular science have led to the discovery of genetic events in soft-tissue tumors that have not only enriched our understanding of the underlying biology of these neoplasms but have also proven to be powerful diagnostic adjuncts and/or indicators of molecular targeted therapy. In particular, many soft-tissue tumors are characterized by recurrent chromosomal rearrangements that produce specific gene fusions. For pathologists, identification of these fusions as well as other characteristic mutational alterations aids in precise subclassification. This review will address known recurrent or tumor-specific genetic events in soft-tissue tumors and discuss the molecular approaches commonly used in clinical practice to identify them. Emphasis is placed on the role of molecular pathology in the management of soft-tissue tumors. Familiarity with these genetic events provides important ancillary testing for pathologists to include in their diagnostic armamentarium.